The present invention relates, in general, to the field of distance measuring equipment. More particularly, the present invention relates to a compact folded signal transmission and image viewing pathway design and visual display technique for laser rangefinding instruments.
Representative implementations of optical pathways for various optical instruments, including laser-based rangefinders, are described in, for example, U.S. Pat. No. 6,236,504 issuing May 22, 2001 for “Method and Device for Adjusting Eye Range by Means of Displacements of Prisms and Ocular Lenses”; U.S. Pat. No. 6,292,314 issuing Sep. 18, 2001 for “Prism System for Image Inversion in a Visual Observation Beam Path”; and U.S. Pat. No. 6,344,894 issuing Feb. 5, 2002 for: “Optical Axis Adjusting Structure for a Range Finder”. Designs representing decided improvements over those described in the aforementioned patents are disclosed in U.S. Pat. No. 7,349,073 for: “Efficient Optical System and Beam Pathway Design for Laser-Based Distance Measuring Device” and U.S. Pat. No. 7,450,282 for: “High Precision Optical System and Beam Pathway Design for a Laser-Based Distance Measuring Device”, both assigned to Laser Technology, Inc., Englewood, Colo., and Kama-Tech (HK) Limited, Hong Kong, China assignees of the present invention, the disclosures of which are herein incorporated by this reference in their entirety.
While generally representative of the current state of the art in such designs, the aforementioned '504, '314, and '894 patents all describe systems of lenses and prisms which are relatively complex to implement, space inefficient, as well as costly to manufacture, assemble and align. Therefore, a need exists for a compact folded signal transmission and image viewing pathway design and visual display technique for laser rangefinding instruments which provides significant advantages over conventional designs while nevertheless providing an accurate foundation for a compact, professional rangefinder having excellent beam transmission/reception and optical properties for use in surveying or other demanding range-finding applications.